The ad, by Golden Era Productions, featured images with different captions on how the church has helped people.
One complainant asked the ASA whether the following claims in the captions were misleading: "teaching 19 million the facts about illicit drugs", "making tens of millions aware of their human rights", and "giving aid to 24 million in times of need".
The ASA concluded that the evidence behind the two former claims was substantial.
However, as the third claim was accompanied with images of a church volunteer who had a stethoscope and was cradling a baby, the ASA said that this came across as the church providing "medical assistance, rescuing victims and providing food, water and shelter".
The church provided the ASA with a list of disaster zones their volunteers have visited and a spreadsheet of the number of people who they helped. But the ASA said that the type of aid differed among the volunteers and that the evidence supplied was anecdotal.
The ruling added: "Because we had not been provided with suitable evidence to show how the specific figure of 24 million had been calculated and that it was accurate, we concluded that the claim had not been substantiated and was likely to mislead viewers.
"We told the Church of Scientology International to ensure they held adequate evidence for any claims that viewers were likely to regard as objective and capable of substantiation."